Growth and characterization of stoichiometric tungsten oxide nanorods by thermal evaporation and subsequent annealing

Abstract

Stoichiometric tungsten oxide (WO(3)) nanorods are synthesized on tungsten (W) substrates by a high-temperature, catalyst-free, physical deposition process and by subsequent annealing in oxygen atmosphere. Tungsten oxide nanorods are grown by thermal evaporation of WO(3) powder at elevated temperature in a tube furnace. XRD, TEM and XPS analysis shows that the as-grown nanorods are single crystalline and non-stoichiometric (WO(x)). Annealing of WO(x) nanorods at 700 °C under oxygen atmosphere has led to the formation of stoichiometric WO(3) as evidenced by XRD, XPS and Raman analysis.

Influence of structural properties on the activity of WO 3 catalysts for visible light photocatalytic ozonation

“…In all cases, the spectra obtained showed a doublet with binding energies around 35.5 and 37.6 eV for W 4f 7/2 and W 4f 5/2 , respectively, with the W 4f 7/2 -W4f 5/2 binding energy separation being 2.1 eV. The energy position of this doublet corresponds to the W 6+ oxidation state in WO 3 (Senthil and Yong, 2007;Lee et al, 2012;Pang et al, 2013). On the other hand, XPS spectra of O 1s spectral region for all the catalysts are shown in Fig.S2.…”

“…This can be noticed by the presence of the contributions centred at 26.5 and 28.6º. These are characteristics of the monoclinic crystalline structure, together with the widening of the peaks at 23.9 and 34.0º that are affected by the overlapped cubic-monoclinic contributions with the formation of the triple peaks in monoclinic phase at these 2θ values corresponding to reflections from (001), (020) and (200) planes (Senthil and Yong, 2007). It is also noticeable that an increase of the calcination time from 5 to 60 min did not produce any significant change in the XRD patterns (W 300 -5 and W 300 -60) which is indicative of the stabilization of the cubic structure at this temperature.…”

“…Due to the lack of C 1s signal, binding energies were calibrated relative to the O1s peak of stoichiometric WO 3 at 530.2 eV (Senthil and Yong, 2007;Pang et al, 2013).…”

Surface Functionalization of WO3 Thin Films with (3-Aminopropyl)triethoxysilane and Succinic Anhydride

“…The peak located at higher binding energies ($41.4 eV) are assigned to W5p 3/2 of the W 6+ ions. 21,[36][37][38][39][40][41][42] Figure 3b shows the XPS of the O 1s core level spectra of the WO 3 thin films. The O 1s core level spectra are clearly asymmetric.…”

“…The lowest intensity peak centered at 532.73 eV (O III ) can be attributed to the chemisorbed oxygen impurities as -CO 3 , adsorbed H 2 O or adsorbed O 2À . 21,[36][37][38][39][40][41][42] Figure 4 shows the FTIR spectra of both the unfunctionalized and functionalized WO 3 thin films: curve (1) is Si/WO 3 ; curve (2) is Si/WO 3 @Solvent- APTES; curve (3) is Si/WO 3 @solvent-APTES-SA; curve (4) is Si/WO 3 @O 2 plasma-APTES-SA; and curve (5) is Si/WO 3 @O 2 plasma-APTES-SA. The detailed FTIR spectra in the wavenumber range of 2000-400 cm À1 are presented in Fig.…”